Search PubMed⌕ Search

Biomedical subjects

F Belardelli

Publications and source records attributed to F Belardelli.

At least 91 records · Page 5Linked to original sources
PubMed1993

Selective alteration of the turnover of interferon beta mRNA in peritoneal macrophages from LPS-hyporesponsive mice and its role in the defective expression of spontaneous interferon.

Basal levels of interferon (IFN)-beta mRNA transcription were detected in both freshly explanted LPS-responsive (Lpsn) and LPS-hyporesponsive (Lpsd) peritoneal macrophages (PM). In vitro cultivation of PM resulted in a time-dependent reduction in the level of IFN-beta mRNA, which was far more rapid in Lpsd than in Lpsn PM. Treatment of Lpsn PM with cycloheximide (CHX) resulted in a marked accumulation of IFN-beta mRNA, which was not associated with an increase in IFN-beta gene transcription. However, treatment of Lpsd PM with CHX did not induce accumulation of IFN-beta mRNA. CHX induced the accumulation of IFN-alpha-4 mRNA in both Lpsn and Lpsd PM, CHX enhanced the accumulation of two cytoplasmic factors interacting with AU-rich sequences within the 3' untranslated region of IFN-beta mRNA. We conclude that Lpsd PM exhibit an impaired capacity to stabilize IFN-beta mRNA that may account for their low expression of IFN-beta.

Animals↗
PubMed1993

Antitumor effect of thymosin alpha 1/interleukin-2 or thymosin alpha 1/interferon alpha,beta following cyclophosphamide in mice injected with highly metastatic Friend erythroleukemia cells.

We investigated the effects of the systemic administration of thymosin alpha 1 plus relatively low doses of human recombinant interleukin-2 or very low doses of interferon alpha,beta in untreated and cyclophosphamide (CY)-treated DBA/2 mice challenged either subcutaneously or intravenously (i.v.) with Friend erythroleukemia cells (FLC). Both treatments resulted in the complete regression of subcutaneous tumor and cured a significative percentage of mice. They also increased the survival time of mice i.v. injected with large numbers of FLC. Neither immunotherapy alone nor CY, alone or in combination with single cytokines, produced similar effects. The antitumor action of these combined chemoimmunotherapy protocols seems to involve activation of the immune response since (a) a synergistic increase of the cytotoxicity of spleen cells was demonstrated in treated mice; (b) selective in vivo depletion of asialo-GM1, CD4, or CD8-positive cells abrogated this antitumor activity; and (c) a high lymphoid cell infiltration was found at the tumor site and in the livers of treated mice.

Animals↗
PubMed1993

Tumour necrosis factor-alpha increases the sensitivity of human immunodeficiency virus (HIV)-infected monocytic U937 cells to the complement-dependent cytotoxicity of sera from HIV type 1-infected individuals; role of the gp120 protein.

Sera of 40 intravenous drug addicts [25 seropositive and 15 seronegative for human immunodeficiency virus (HIV)] were tested for the presence of cytotoxic antibodies against uninfected and HIV-infected monocytic U937 cells. Six of the 25 seropositive samples proved to be cytotoxic for HIV-infected target cells in the presence of complement. The pretreatment of HIV-infected U937 cells with tumour necrosis factor (TNF)-alpha (which enhances virus production in these cells) increased the detection of serum cytotoxicity and 60% of these sera became cytotoxic. The percentage lysis was also increased after the TNF-alpha treatment of the target cells (from 16.2 +/- 4.5 to 71.2 +/- 4.9). The complement-dependent cytotoxic activity of these sera was significantly reduced by pretreatment with recombinant HIV gp120 antigen. This reduction was dose-dependent in the majority of cases. Immunofluorescence studies suggested that the cytotoxic sera mainly interacted with the viral antigens localized on the membrane of HIV-infected TNF-treated U937 cells. Moreover, comparative Western blot analyses using cellular extracts from untreated and TNF-treated U937 cells showed that there was a positive correlation between the cytotoxic phenotype and the capacity of sera to recognize the gp120 protein in extracts from TNF-treated HIV-infected cells. These results suggest that in some circumstances endogenous TNF-alpha can be a protective factor because it can render persistently infected cells highly sensitive to complement-dependent serum cytotoxicity as a result of increased expression of the relevant viral antigen (gp120) on the cell membrane.

Acquired Immunodeficiency Syndrome↗
PubMed1993

Monocytotoxic antibodies in HIV-infected persons. TNF-alpha treatment of U937 cells increases the complement dependent cytotoxicity.

Sera of 40 intravenous drug addicts were tested for the presence of cytotoxic antibodies against uninfected and HIV-infected monocytic U937 cells. Twelve out of 31 seropositive samples proved to be cytotoxic for HIV-infected, untreated target cells in the presence of complement. The TNF-alpha treatment of HIV-infected U937 cells increased the detectability of cytotoxic effect of sera (21/31). The complement dependent cytotoxic activity of sera was reduced by pretreatment with recombinant HIV gp120. This reduction proved to be dose-dependent in the majority of cases. Immunofluorescence studies indicated that the cytotoxic sera interacted with antigens mostly localized on the cell membrane of HIV-infected TNF-alpha treated U937 cells. The specificity, the possible role and origin of monocytotoxic antibodies in HIV-infected persons is discussed.

Binding, Competitive↗
PubMed1992

Interferon-alpha/beta in virus-induced mouse mammary carcinogenesis: effects on the spontaneous process and on the progression of transplanted pre-neoplastic lesions.

Low levels of anti-viral activity, mainly interferon alpha/beta (IFN-alpha/beta), are regularly found in lymphoid tissues of BALB/c mice infected with the C3H strain of mammary tumor virus. At the time of tumor development, significant amounts of anti-viral activity were detected in homogenates of spleen and mammary tumors, but not in blood and normal mammary glands. This activity is pH2-resistant and neutralized by antibody to IFN/alpha-beta. The pathogenetic role of IFN in mammary carcinogenesis was investigated in 2 ways: (a) by treating virus-infected newborn mice with antibody to IFN-alpha/beta, and (b) by giving either the latter antibody or IFN-alpha/beta to virus-free animals transplanted with pre-neoplastic lesions. Mice were treated only for 2 months, starting either 1 week after birth or immediately after tumor transplant. In case (a), treatment with antibody to IFN-alpha/beta shortened the incubation period of mammary carcinomas and decreased the mean survival time. In case (b), anti-IFN antibody did not significantly affect the development of mammary tumors. However, exogenous IFN-alpha/beta markedly reduced both tumor incidence and mortality rate. These results indicate that endogenous IFN-alpha/beta plays a crucial role in the in vivo restriction of the early infectious phase of spontaneous carcinogenesis and that relatively high doses of IFN-alpha/beta may inhibit the progression of pre-neoplastic lesions.

Aging↗
PubMed1992

Inhibition of Friend leukemia cell visceral metastases by a new monoclonal antibody and role of the immune system of the host in its action.

We developed a syngeneic mouse IgG2a monoclonal antibody (MAb) A9D41 directed against the Friend leukemia virus envelope gp70 antigen present on the cell surface membranes of virus producer 3C18 Friend leukemia cells (FLC). A9D41 showed a marked antitumor activity in DBA/2 mice given injections of gp70 positive 3C18 FLC, but it was ineffective in mice given injections of gp70 negative 745 FLC or unrelated tumor cells. A9D41 was particularly effective in inhibiting the development of 3C18 FLC liver and spleen metastases. MAb was also effective as adjuvant therapy in inhibiting visceral metastases after excision of an established s.c. FLC tumor, and combined therapy of A9D41 with mouse interferon alpha/beta was more effective than MAb or interferon alpha/beta alone. The immune system of the host played a decisive role in the antimetastatic action of A9D41. Thus, although MAb was cytotoxic for 3C18 FLC in vitro in the presence of rabbit complement, the F(ab')2 fragment was ineffective in vivo, and the antitumor effect of MAb was abolished in mice treated with an antibody to CD4 and diminished in natural killer cell-deficient beige and athymic nude mice. MAb-treated mice surviving injection of FLC developed an immune response to 3C18 FLC.

Animals↗
PubMed1992

Spin-lattice relaxation in murine tumors after in vivo treatment with interferon alpha/beta or tumor necrosis factor alpha.

1H NMR spin-lattice relaxation times (T1) were measured in vitro and in vivo in Friend leukemia cell tumors during subcutaneous tumor growth in syngeneic mice and after in vivo administration of either purified murine interferon alpha/beta (IFN) or recombinant tumor necrosis factor alpha (TNF). Untreated tumors exhibited monoexponential T1 relaxation independently of tumor age at least until Day 16 after implantation. Histological examinations showed that under these conditions tumors were highly homogeneous and substantially free of necrotic areas. Peritumoral administrations of either IFN or TNF did not significantly alter the tumor relaxation properties at early stages of inhibition of tumor growth. The longitudinal relaxation decay became instead clearly biexponential at later stages (more than 7 days of IFN treatment or 2 days after TNF administration). While the T1 relaxation behavior could be unequivocally correlated with the presence of necrotic areas in these tumors, it could not be considered as an early marker of the altered growth capability, induced by administration of either IFN or TNF.

Animals↗
PubMed1992

Cyclic AMP-mediated inhibition of vesicular stomatitis virus and herpes simplex virus replication in mouse macrophage-like cells.

In this study, we have analysed the effects of cAMP inducers on the multiplication of vesicular stomatitis virus (VSV) and herpes simplex virus type 1 (HSV-1) in mouse macrophage-like cells. The addition of dibutyryl cAMP (dB-cAMP) or cholera toxin to resting peritoneal macrophages aged in vitro or P388D1 cells resulted in a 10- to 100-fold reduction of VSV yield compared to control cultures. In contrast, no cAMP-dependent inhibition was found in VSV-infected L929 cells. In macrophage-like cells, the dB-cAMP-induced antiviral state was not inhibited by antibodies to interferon (IFN)-alpha/beta and did not correlate with any increase in the intracellular levels of 2-5 oligo(A) synthetase. Dibutyryl cAMP did not inhibit virus yields in mouse macrophages infected with encephalomyocarditis virus. In P388D1 cells, the addition of dB-cAMP resulted in an approximately 10-fold inhibition of HSV-1 replication with respect to control cultures, as evaluated both by TCID50 and plaque assays on Vero cells. Dibutyryl cAMP did not affect VSV binding or entry into mouse macrophages and the cAMP-mediated anti-VSV state was significantly reduced by inhibitors of protein kinase C (i.e. staurosporine and H7). These data suggest that macrophages may acquire resistance to infection by VSV and HSV-1 after treatment with cAMP inducers. This cAMP-mediated antiviral activity does not depend on the modulation of the endogenous IFN system, suggesting that macrophages exhibit multiple resistance mechanisms (i.e. IFN-dependent and IFN-independent) to maintain their intrinsic antiviral activity.

2',5'-Oligoadenylate Synthetase↗
PubMed1992

Persistent infection of normal mice with human immunodeficiency virus.

In this article, we report the establishment of persistent HIV type 1 infection of normal Swiss mice after a single intraperitoneal injection with high-producing HIV-infected U937 cells. Anti-HIV antibodies were found more than 500 days after the original injection, and p24 antigenemia was detected in approximately 50% of the mice. By polymerase chain reaction (PCR) techniques, HIV-specific gag and env sequences were detected in DNA samples from peripheral blood mononuclear cells (PBMC) and peritoneal cells of seropositive mice 300 to 500 days after inoculation with HIV-infected cells. These DNA samples did not contain human DNA sequences, as determined by PCR analysis using primers and the probe for the HLA-DQ alpha gene. Low levels of p24 and detectable human reverse transcriptase activity were found in cultures of PBMC and peritoneal macrophages. Cocultivation of PBMC, peritoneal cells, and spleen cells with human uninfected U937 or CEM (a T lymphoma cell line) cells resulted in HIV infection of the target cells, as determined by PCR analysis and/or p24 assays. The intravenous injection of untreated Swiss mice with the PBMC from PCR-positive mice resulted in the development of an increasing antibody response to HIV in the recipient animals. Together these results indicate that cells from seropositive Swiss mice were persistently infected with HIV and were capable of producing infectious virus. The development of persistent HIV infection in an immunocompetent mouse may represent the starting point for further studies aimed at defining the host mechanisms involved in the restriction of virus replication, defining the pathogenesis of HIV infection, and testing antiviral compounds and vaccines.

Animals↗
PubMed1991

Synergistic anti-tumor effects of combined IL-1/IFN-alpha/beta therapy in mice injected with metastatic Friend erythroleukemia cells.

Peritumoral injection of relatively low doses of either mouse interferon (IFN)-alpha/beta (10,000-20,000 units/injection) or of recombinant human interleukin-1 (IL-1) beta (125-250 ng/injection) in mice transplanted s.c. with Friend erythroleukemia cells (FLC) resulted in some inhibition of primary tumor growth, inhibition of liver and splenic metastases and increased survival time. A synergistic anti-tumor effect was observed in mice injected with both IL-1 and IFN-alpha/beta. Highly purified mouse IFN-beta also exerted a synergistic anti-tumor effect when combined with IL-1-beta in mice injected with FLC. The anti-tumor action of IL-1/IFN was markedly reduced in mice treated with antibodies to CD4 antigens. Antibodies to asialo-GM1 also diminished the anti-tumor effect by the combined cytokine treatment. The combined IL-1/IFN therapy was effective in NK-deficient bg/bg mice, although the extent of the anti-tumor response in these mice was less than that observed in bg/+mice.

Animals↗
PubMed1991

Host humoral and cellular immune mechanisms in the continued suppression of Friend erythroleukemia metastases after interferon alpha/beta treatment in mice.

DBA/2 mice were injected intravenously with 2 x 10(6) 3C18 Friend erythroleukemia cells (FLC), a cell line resistant to interferon alpha/beta (IFN-alpha/beta). Although daily administration of mouse IFN-alpha/beta markedly increased the mean survival time, most IFN-treated mice continued to harbor FLC in different organs. To investigate the mechanisms responsible for this persistent suppression of FLC growth in IFN-treated mice, we undertook a series of adoptive transfer experiments with sera and spleen cells. Sera from FLC-injected, IFN-treated mice were very effective in conferring protection on DBA/2 mice even when injected systemically (intravenously) 18-24 h before intravenous challenge with FLC. These sera also exhibited antitumor activity when injected subcutaneously or intraperitoneally together with FLC. The protective factor in serum was shown to be an immunoglobulin. FLC-injected, IFN-treated mice developed antibodies to FLC demonstrable by radioimmunoassay and complement-dependent cytotoxicity. Sera from these mice recognized a specific 65-kD FLC membrane antigen(s) not detectable on membrane extracts from RBL-5 or ESb tumor cells, or on normal spleen cells. FLC-injected, IFN-treated mice also developed a specific cellular response demonstrable by transfer of protection with spleen cells injected intravenously or subcutaneously. Analysis of the responsible spleen cell populations indicated that the effector cells were neither T nor B cells. These results demonstrating the importance of host humoral and cellular immune mechanisms in the persistent suppression of FLC in IFN-treated mice may be relevant to the use of IFN-alpha/beta in patients in whom tumors may regress and tumor cells may then remain latent for extended periods of time.

Animals↗
PubMed1991

Posttranscriptional regulation of interferon mRNA levels in peritoneal macrophages.

Low levels of beta interferon (IFN) mRNA are transcribed in freshly explanted murine peritoneal macrophages. Nuclear runoff transcription assays show that this "constitutive" IFN-beta-mRNA transcription does not increase in macrophages treated either with lipopolysaccharide or with IFN-gamma, which induce a marked accumulation of this mRNA and greatly increase IFN secretion. Therefore, these agents promote accumulation of IFN-beta mRNA by posttranscriptional mechanisms. The IFN-alpha 2 gene is also constitutively transcribed by macrophages, but the corresponding mRNA does not accumulate in lipopolysaccharide-treated cells.

Animals↗
PubMed1991

Human immunodeficiency virus (HIV)-infected tumor xenografts as an in vivo model for antiviral therapy: role of alpha/beta interferon in restriction of tumor growth in nude mice injected with HIV-infected U937 tumor cells.

The host factors involved in the restriction of tumor growth were studied in nude mice transplanted with a cloned line of chronically human immunodeficiency virus (HIV)-infected U937 cells. HIV-infected and uninfected U937 cells exhibited the same growth patterns in culture. However, HIV-infected cells were not tumorigenic when injected subcutaneously in nude mice, whereas large solid tumors were observed in mice injected with uninfected U937 cells. Injection of nude mice with antibody to alpha/beta interferon (IFN-alpha/beta) enabled HIV-infected U937 cells to grow progressively in approximately 90 to 100% of mice. HIV-infected U937 cells formed solid tumors in the majority (60 to 90%) of either immunosuppressed (splenectomized, irradiated, and anti-asialo-GM1-treated) or genetically immunodeficient (bg/nu/xid) nude mice. In mice treated with antibodies to IFN-alpha/beta with established HIV-positive tumors, a direct correlation was found between p24 antigenemia and tumor size. Treatment of established HIV-positive U937 cell tumors with human IFN-alpha or mouse IFN-alpha/beta resulted in a clear-cut inhibition of both tumor growth and p24 HIV antigenemia. In contrast, treatment with tumor necrosis factor alpha markedly inhibited tumor growth but did not significantly decrease serum p24 levels. 3'-Azido-3'-deoxythymidine treatment did not affect either tumor growth or the levels of serum p24 antigen. These data indicate that endogenous IFN-alpha/beta is a crucial factor in the restriction of both tumor growth and p24 antigenemia in mice injected with HIV-infected tumor cells. Moreover, the results suggest that the development of HIV-1 p24 antigenemia in athymic immunosuppressed mice may represent an interesting in vivo model for anti-HIV therapy.

Animals↗
PubMed1991

Growth properties, differentiation capacity and oncogene expression in metastatic and nonmetastatic Friend leukemia cell variants.

The aims of this study were: (1) to characterize the biologic properties of the WGA-resistant (WR) Friend leukemia cells (FLC) as compared to the original nonmetastatic or highly metastatic FLC; (2) to investigate the possible correlations between the expression of some oncogenes (i.e., c-myc, H-ras and K-ras) and the in vitro and in vivo behavior of FLC. The tumorigenic behavior of the different FLC types strongly depended on the site of tumor injection. Both WR FLC and in vitro passaged FLC did not grow as ascites (when injected intraperitoneally) and developed large solid tumors (when injected subcutaneously), without forming any spleen or liver metastasis. In contrast, in vivo passaged FLC rapidly formed hemorrhagic ascites when injected intraperitoneally; the subcutaneous injection of these cells resulted in the development of solid tumors, which were smaller than the other FLC tumors, but capable of metastasizing to the liver and to the spleen. No significant differences were observed in the in vitro growth characteristics and cell cycle parameters among the different FLC types under various experimental conditions (i.e., FCS concentration or cell seeding densities). Similarly to the metastatic in vivo passaged parental cells, WR FLC exhibited a much lower erythroid differentiation after in vitro addition of either dimethyl sulfoxide or hexamethylene bisacetamide than the in vitro passaged FLC. High levels of c-myc oncogene mRNA were expressed in all FLC variants; no major variations in the c-myc expression were observed in FLC cultivated in medium supplemented with different FCS concentrations and/or seeded at various cell densities. In addition, no changes in the expression of H-ras or K-ras were observed between the different FLC types.

Acetamides↗
PubMed1991

Influence of the site of tumor growth on the capacity of a low tumorigenic line of Friend erythroleukemia cells to differentiate.

Friend erythroleukemia cells (FLC) passaged in mice are highly tumorigenic and multiply extensively in the livers of suckling DBA/2 mice without differentiating. In contrast, in vitro passaged FLCs injected intravenously were of low tumorigenicity, multiplied to a limited extent in the livers of suckling mice, and underwent marked differentiation from the proerythroblast to the orthochromatic erythroblast stage in the liver. The presence of characteristic C-type virions budding from the cell surface in various stages of erythroid differentiation served as a marker of the injected FLCs. When the same in vitro passaged FLCs that differentiated in the liver were injected subcutaneously in suckling mice, they formed large subcutaneous tumors consisting of sheets of undifferentiated tumor cells. It is concluded that the tumorigenicity of FLCs depended on the site of tumor growth and that there is an inverse correlation between the tumorigenic capacity and the capacity to differentiate.

Animals↗
PubMed1990

Anti-tumor effects of interferon in mice injected with interferon-sensitive and interferon-resistant Friend erythroleukemia cells. VIII. Role of the immune system in the inhibition of visceral metastases.

DBA/2 mice were injected i.v. with IFN alpha/beta-resistant 3CI8 Friend erythroleukemia cells (FLC) which metastasize to the liver and spleen. IFN alpha/beta treatment of FLC-injected mice increased their survival time and these mice developed a resistance to a second challenge with FLC. The efficacy of IFN alpha/beta in increasing the survival time was compared between normal immunocompetent and immunodeficient mice. The anti-tumor action of IFN was markedly reduced or abolished in newborn DBA/2 mice, in adult athymic nu/nu and beige DBA/2 mice, and in BALB/c scid/scid mice. To determine the phenotype of the effector cells involved, FLC-injected DBA/2 mice were treated with antibodies to asialo-GMI, CD4, or CD8 antigens, or with cyclosporin A or silica. IFN alpha/beta treatment proved much less effective in these mice, indicating that a variety of effector cell types participated in the IFN-induced suppression of visceral metastases. Thus, an intact immune system appears to be essential to obtain optimal therapeutic effects of IFN alpha/beta in this experimental model.

Animals↗
PubMed1990

Importance of interferon alpha in the resistance of allogeneic C57B1/6 mice to the multiplication of Friend erythroleukemia cells in the liver.

Friend erythroleukemia cells (FLC) (H-2d) injected intravenously multiply extensively in the livers of syngeneic DBA/2 mice and not at all in the livers of allogeneic C57B1/6 mice. Our results indicate that interferon alpha (IFN-alpha) is an important factor in the resistance of allogeneic mice to the multiplication of FLC in the liver. (a) After i.v. inoculation of FLC there was an inverse correlation between the presence of IFN-alpha in the serum and the capacity of FLC to multiply in the liver. Thus, all 44 FLC-injected adult C57B1/6 mice had circulating IFN-alpha and FLC did not multiply in the liver of any of the mice. Interferon was not detected in the serum of 83% of 41 FLC-injected DBA/2 mice (and was found only at a low titer in 17% of the mice) and FLC multiplied in the liver of all mice. (b) FLC did multiply in the livers of newborn C57B1/6 mice and in the livers of irradiated adult C57B1/6 mice, and IFN-alpha was not detected in their sera. In contrast, after i.v. inoculation of FLC, IFN-alpha was detected in the sera of 3-week-old and athymic nu/nu adult C57B1/6 mice while FLC failed to multiply in the liver. (c) FLC also induced IFN-alpha in congenic B10.D2 (H-2d) mice and FLC did not multiply in the liver. We suggest that, depending on the site of tumor implantation, different host mechanisms have various degrees of importance in controlling the growth and/or rejection of allogeneic tumor cells, and that IFN-alpha is particularly important when FLC are injected i.v.

Age Factors↗